Rice straw return technology is being vigorously promoted and applied.

Vigorously promoting rice straw return is one of the most economical and effective ways to recycle nutrients through the soil-crop-soil cycle. It not only plays a very important role in improving soil and building up soil fertility, but also has great significance for improving soil potassium and silicon nutrient conditions, balancing crop nutrition, and alleviating the contradiction between the shortage of potassium fertilizer resources in our country and the excessively rapid rise in chemical fertilizer prices.

1. Increasing soil organic matter content. Rice straw has a high organic matter content. Generally, dry rice straw has an organic matter content of 40%. After being returned to the field, it is beneficial to the accumulation and renewal of soil organic matter. According to the results of our 3 consecutive years of positioned trials: when 150 kg of dry rice straw is applied per 667 sq m, and soil is sampled and tested each year after the late rice harvest, the soil organic matter content increases year by year. The increase in the 1st year is relatively high, at 0.11%-0.12%, and the 3-year average increase is 0.06%-0.09%. From the perspective of soil humus composition, after rice straw return, free, loosely bound, stably bound, and tightly bound humus all increase, among which the proportions of free and loosely bound humus increase relatively greatly. The accumulation of various forms of humus in the 2nd and 3rd years is also the same. This shows that rice straw return can not only increase the quantity of soil humus, but also improve the quality of humus.

2. Improving soil physical properties. Because rice straw return increases the accumulation of soil organic matter, under the action of microorganisms, this organic matter forms humus through a series of decomposition and transformation processes. It aggregates with clay minerals into organic-inorganic composite colloids, and thus soil structure is improved. The positioned trial results show that when 150 kg of dry rice straw is applied continuously for 3 years per 667 sq m of paddy field, and the available potassium content of the plants is measured at the late rice tillering stage, its available potassium content is 243 mg per kg higher than that without application. Compared with the control, the late rice plants with early rice straw return are 3 cm-8 cm taller, the heading stage is 2 days-4 days earlier, the seed-setting rate is increased by 3.8 percentage points compared with the control, and leaf brown spot disease is significantly reduced, with no potassium deficiency symptoms.

4. Increasing the content of available silicon in soil. The trial results show that when 150 kg of dry early rice straw is applied per 667 sq m of paddy field, and soil available silicon content is measured from samples taken 6 times at each growth stage of late rice, the average result is that the available silicon content per kg of soil with rice straw return is 75.8 mg higher than that without rice straw application. For the silicon uptake of rice plants, the average result of 3 analyses is that the silicon uptake of rice plants per kg with rice straw return is 22 g higher than that of the control.

5. Enhancing the activity of microorganisms in soil. After rice straw return, because the fresh carbon source in the soil increases sharply, the organic energy available for the life activities of soil microorganisms increases, various groups of microorganisms multiply in large numbers, and when rice straw return is combined with nitrogen fertilizer application, the phosphorus-to-nitrogen ratio is coordinated, and the amount of microbial proliferation is even greater. When the total amount of soil microorganisms is measured at the late rice tillering stage, the total amount of microorganisms in soil with early rice straw return is 64.8% higher than that in soil without rice straw application.

6. Enhancing soil enzyme activity. The life activities of soil microorganisms are the basis for the formation and accumulation of enzymes in soil. After rice straw return, soil microorganisms increase greatly, and the activities of catalase and invertase in soil are significantly improved. Because enzymatic reactions are enhanced, this accelerates the decomposition of organic matter and the transformation of mineral nutrients in soil, and the utilization rates of nutrient elements such as nitrogen and phosphorus in soil are improved.